Steel and method of making the same



Patented Jan. 1, 1935 s'mnannnmrno 0F Wilbert E. Davis and George E. Hitchens, McKeesport, Pa., assignors to National Tube Comp 1.: a corporation oi New Jersey 1% Drawing. Application Serial No. 662,000

This invention relates to an improved steel and method of making the same.

One object of the present invention is to provide a steel having desirable characteristics heretofore unobtainable by any of the well known methods. It is a well known fact that open-hearth stee and Bessemer steelare each possessed of certain desirable characteristics not found in the other; as, for instance,'the former is more ductile than'the latter.

In the manufacture of certain classes of tubular products, such as conduit, etc., it is found that Bessemer. steel--will thread and electroplate very satisfactorily, but is stiflf and brittle and consequently hard to bend. Openhearth steel, on the other hand, will bend more easily but does not thread or electroplate as satisfactorily as Bessemer steel. Accordingly. it has been the practice in the past to select the steel having the most desirable characteristics for certain purposes, which has meant, of course, that, while not quite so marked, certain undesirable features must necessarily be present. In accordance with the teachings of the present invention, however, these difiiculties are obviated and a steel is obtained having all of the desirable characteristics.

Another object is to provide a method of making steel in which the physical properties of the metal may be more satisfactorily controlled, particularly the phosphorus content, which has an eflect upon ductility and consequently produces a steel which will bend easily without being brittle.

The improved steel of the invention is characterized by including the following elements in substantially the proportions specified:

Car .04 to .09 Manganese -1 .30 to .60 Phosphorus not over .060 Sulphur not over .060

and may be obtained in a number of difierent ways as, for example, by addingphosphorus, sulphur and manganese. to a low carbon steel.

However, the steel. of the invention may be obtained by mixing low carbon basic open hearth steel and low carbon acid Bessemer steel. The

(Cl. -45) I Low carbon basic open-hearth steel Carbon .03 Manganese .11 Phosphorus .005 5 Sulphur .031

Low carbon acid Bessemer steel Carbon .03 Manganese. .07 Phosphorus .069 Sulphur .035

The two steels are mixed together in a ladle by adding the Bessemer steel to the open-hearth steel, or adding the bpen-hearth steel to the 15 Bessemer steel, but preferably by pouring the Bessemer steel intothe open-hearth steel, as this retains the gases which are present in the former and allows them to escape after being teemed from the ladle into a mold, which causes the'proper rimming action and solidification of the ingot.

Immediately the open-hearth steel is poured into the ladle, any portion of the required ferromanganese is added. The ladle is then transferred to the Bessemer converter, which has been blown in the usual manner. The Bessemer steel is then poured into the ladle containing the open-hearth steel and the remaining portion, if any, of the ferro-manganese is added. The steel mixture maythen be teemed from the ladle into suitable molds.

An analysis of the mixture of the above referred to typical heats of open-hearth and Bessemer steels is as follows:

Mixed ea:

Carb n Manganese Phosphorus .030 Sulphur .032

The change in the analysis of carbon and manganese in' the mixed steel is due to the carbon and manganese in the ferro-manganese which is added to' the ladle. This gives the desiredv carbon and manganese in the finished steel.

It is to be understood that by varying the proportions of each steel that the phosphorus content may be changed, and' by recarburizing with ferro-manganese or other recarburizers in the ladle a. steel can be p d with Varying amounts of manganese and carbon. The sulphur and silicon is practically the same in both the open-hearth and Bessemer steels, and remains the same in the mixed steel. These ingredients can also be varied by adding sulphur or ferro-silicon to .the ladle.

In the manufacture of tubular products the physical properties of the metal are tested by subjecting the crop-ends of the product to crushing between parallel plates to one-third of its diameter. If the product cracks at the point of maximum bend it is rejected. A comparison of acceptable ductility between the results of crushing tests on the various steels is as follows:

Open-hearth steel 100.00 Bessemer steel 75.7 The steel of the invention 97.3

Experience has shown that when the steel of this invention is made by mixing low carbon basic open-hearth steel and low carbon acid Bessemer steel in the ladle the Bessemer steel steel is poured into low carbon acid Bessemer steel, the ductility of the resulting steel would prove to be only 57.1 when. compared with openhearth steel.

This latter result is due to the fact that when the basic open-hearth steel is poured into the acid Bessemer steel the. gases in the Bessemer steel are partly removed by the violent agitation of the metal, and there is not suflicient-action when teemed into the mold to allow the gases to escape, consequently making a tendency for the steel to rise in the mold, which causes the blow. holes to be too close to the surface. This, of course, results in a product with a defective surface, and one which'does not have the required physical properties.

While we have shown and described several specific embodiments of our invention it will be understood that we do not wishtobe limited exactly thereto, sincevarious modifications may be made without departing from the scope of our invention, as defined in the following claims.

We claim: 4

1. The method of making steel containing approximately .04 percent to .09 percent carbon; .30 to .60 percent manganese; less than .060 percent phosphorus; less than .060 percent sulfur; the remainder being iron and the usual traces of residual ingredients such as silicon which includes adding low carbon Bessemer steel to a substantially equal quantity of low carbon basic open-hearth steel.

2. The method of making steel containing approximately .04percent to .09 percent carbon; .30 to .60 percent manganese; less than .060 percent phosphorus; less than .060 percent sulfur; the remainder being iron and the usual traces of residual ingredients such as silicon which includes recarburizing low carbon open-hearth steel, and adding thereto a substantially equal quantity of low carbon Bessemer steel.

3. The method of making steel containing approximately .04 percent to .09 percent carbon; .30 to .60 percent manganese; less than .060

percent phosphorus; less than .060 percent sulfur; the remainder being iron and the usual traces' of residual ingredients such as silicon which includes recarburizing low carbon openhearth steel, adding thereto a substantially equal quantity of low carbon Bessemer steel, and recarburizing the combined open-hearth and Bessemer steels.

4. The method of making steel containing approximately .07 percent carbon; .35 percent manganese; .039 percent phosphorus; .032 percent sulfur, the remainder being iron and the usual traces of residual ingredients, such as silicon, which includes adding low carbon Bessemer steel to a substantially equal quantity of low carbon basic open-hearth steel.

5. The method of making steel containing approximately .07 percent carbon; .35 percent manganese; .039 percent phosphorus; .032 S111? steel, and recarburizing the combined open- 7 hearth and Bessemer steels.

' WILBERT F. DAVIS. v

GEORGE E.,HITCHENS. 

